Aviation lights for air fields, landing zones and obstructions or hazards to flight safety must meet detailed requirements for directional field of illumination, intensity distribution, color, duty cycle, pulse repetition rate, control, electrical, mechanical and environmental performance and durability. The United States Federal Aviation Administration (FAA) and international regulatory bodies govern the regulations, test and certification procedures for photometric, systems performance and durability.
The photometric requirements of lights and luminaire assemblies for specific purposes of aviation navigation, landing, take-off and flight control have detailed specifications for the distribution of light intensity dependent upon the placement and application. In order to meet the specifications for each type of luminaire, manufacturers typically use external optics to modify the illumination pattern from the light source (single or array of thermal, arc, or solid state devices) peculiar to the application. Conventional aviation obstruction lights employ lenses and/or mirrors with light sources to produce directional illumination patterns and intensity distributions for navigation aid to pilots and avionics systems within a design field of view for specific flight operation scenarios. The specifications for aviation obstruction lights on buildings, towers and other structures located away from air fields and landing zones include both requirements for intensity distribution in the field of view of the pilot and avionics, and restrictions on environmental light pollution or ground scatter sometimes referred to as residential annoyance factor. Conventional methods of optical systems design for mitigating ground scatter include off-axis optical elements, optics that tilt the optical axis, and baffles to vignette extraneous light illumination from the lower edges of the field of illumination incident on the ground and surrounding residential and commercial areas (e.g., Dialight and Hughley & Phillips).